In U.S. Pat. Nos. 4,049,033 and 4,088,166, among others, a molded collapsible solution container is disclosed which collapses relatively easily under low suction pressures, and thus finds particularly desirable use as a container for parenteral solutions.
It is particularly desirable for the collapsibility of the container to be as complete as possible at the low suction pressures generated by, for example, a two to three foot suction head of water or a desired parenteral solution, even when the container is made of a relatively stiff polyolefin plastic or the like which customarily has not been thought of being useful for making a container which completely collapses under such a low suction pressure head.
In parenteral solution administration, if flow of solution through the needle residing in the vein of a patient terminates, the needle will fill with clotted blood in a short period of time.
In accordance with this invention, as a specific, useful characteristic of the container of this invention, when it is collapsed to its almost completely empty configuration, the rate of draining of the container at a constant suction pressure head decreases substantially, but does not completely terminate, for a significant period of time. Accordingly, the container may be designed for parenteral solution therapy with a 1,000 ml. or other desired dosage capacity, but optionally also with a small amount (for example 50 ml.) of extra capacity of parenteral solution). Accordingly, the container of this invention can be designed so that about 900 ml. or more of parenteral solution can be administered normally, but in the event that the nurse does not arrive at the time of termination of the administration of the 900 ml., the administration flow does not altogether cease, but merely slows down for the last 150 ml. or so, with the result that clotting of the needle is prevented, as takes place when no flow is passing through the administration set. At the same time, because of the reduced flow following the administration of the basic amount of solution, there is no serious overdose of the patient.